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Ready, steady, evolve

By Bob Holmes

DESPITE its universal role in biology, evolution still poses some pretty perplexing questions. Take changes in body form. Every tree or beetle or mouse looks the way it does because thousands of genes turned on at exactly the right time and place to guide the organism from single cell to adulthood. But if body plans are the product of such intricately orchestrated programs, how can evolution ever conjure up new ones? Any slight perturbation would surely send a species tumbling from its evolutionary peak into the barren valleys beneath.

Plants and animals may have hit on an ingenious solution – bottling up evolution for times when they really need it. By squirrelling away genetic mutations, the raw material of evolution, and releasing them all at once, species may be able to leap from peak to evolutionary peak without ever having to slog through the valleys between. This happy knack increases their odds of surviving stressful conditions – nothing less than evolution on demand.

On the face of it, the idea sounds like biological heresy. Plants and animals couldn’t have that sort of control over the random process underlying evolution, could they?

Surprisingly, they could. Over the past few years, a handful of lab experiments have thrown up convincing evidence that organisms really can save up mutations for a rainy day. If the same thing happens in nature, then plants and animals have hit on a way to seize the throttle of evolution, accelerating it when necessary and slowing it down when not. Their storehouse of mutations may also prove to be a treasure trove of new genes for drug …